1. Field of the Invention
This invention is directed to an emergency traction device for vehicles which comprises a traction material such as sand formed into a flat, sheetlike rectangular block held together with a suitable binder. The device is placed in front or back of a wheel of a vehicle which is stuck on ice or snow, or other slippery surface where improved traction is needed. The rotation of the tire in contact with the device causes it to be ground into traction-producing material which spreads under the tire to improve traction.
2. Description of the Related Art
U.S. Pat. No. 4,231,791 issued to Schaaf et al shows a traction device comprising a plastic bag containing sand, and having a foam or sponge rubber pad on one side. Rotation of the adjacent vehicle wheel is said to cause the bag to rupture and spread sand under the wheel. This device leaves fragments of the plastic bag and the foam or sponge on the roadway, creating non-biodegradable litter. Efforts to retrieve all the fragments and pieces under adverse winter conditions would create a serious inconvenience, and the litter would probably be left on the roadway to enter and clog storm sewer systems. The only residue left using the subject invention is sand and a completely biodegradable, water soluble binder, neither of which create serious environmental problems.
A number of other patents are directed to traction devices for vehicles, but all of these are nondestructible articles intended for re-use. The following patents are typical of such reusable traction devices:
______________________________________ Johnson 1,468,023 1923 Griswold 3,202,358 1965 Coale 3,708,117 1973 Botbol 3,836,075 1974 Fosteris 4,121,765 1978 Witt et al 4,223,835 1980 Fontaine 4,650,115 1987. ______________________________________
Johnson's traction plate is composed of sheet steel, and would be expensive to manufacture, and difficult to handle, since it is relatively long and heavy, and it is rigid. Griswold's traction pad is a sheet of rubberized cloth in pad form which has been coated with a flexible layer of rubber or plactic and embedded abrasive. Coale is similar to this, but includes a smooth-bottom tongue for easy insertion under a vehicle wheel. All of the above patents require that the vehicle operator, or some other person, recover the traction devices after each use, which would usually require stopping, and possibly getting stuck a second time.
Botbol is directed to a series of metal plates which are locked together to provide a longer than normal traction path. The Botbol device appears to be complex and expensive to manufacture. Fosteris describes an ice mat made of a flexible rubber-like material, and includes elongated metal strips imbedded in the mat, and rib members extending transversely across the mat and riveted to it. Also included in the Fosteris device are ice gripping elements on the bottom of the mat. This device would also be relatively expensive to manufacture, and appears to be somewhat clumsy to handle, and to store for re-use. Accumulated mud, ice and snow would have to be removed before replacing it in the vehicle, an unlikely step in cold, snowy and icy weather.
Both Witt and Fontaine are directed to traction devices similar in general principles to those described above. Witt's traction-type pad includes a metal "starter plate" which would add to the manufacturing cost. Fontaine's traction mat is almost like a giant, flexible metal watchband, which would, again, be very expensive to manufacture, and would be difficult to keep clean between uses, since it has many cavities and parts in which mud, snow and ice can lodge.
The subject invention eliminates all of the above problems. It is not necessary to get stuck a second time by stopping to recover the traction device of this invention after use. The materials of this invention are environmentally acceptable, and no litter is left behind on the roadway, such as is the case with the Schaaf et al device, which appears to leave fragments of the plastic bag and sponge or foam, unless the vehicle operator stops again to recover these.